Skin Cancer (Hemangiosarcoma) in Cats


PetMD Editorial

Published Mar. 26, 2010

Hemangiosarcoma of the Skin in Cats


The endothelial cells make up the layer of cells collectively referred to as the endothelium, which lines the inner surface of blood vessels, including, but not limited to, the veins, arteries, and intestines. These cells are responsible for the smooth flow of blood within the lumen (interior space) of all of the body's inner structures and tubular spaces. A hemangiosarcoma of the skin is a malignant tumor which arises from the endothelial cells. As the endothelial cells line the entire circulatory system, a hemangiosarcoma can occur at any point in the body.


Because this type of sarcoma grows from the blood cells, the growths themselves are filled with blood. This accounts for the dark blue or red coloring of the mass. If the growth is limited to the outer layer of skin, where it can be removed entirely, the prognosis may be guardedly optimistic, but because of the highly metastatic nature of this cancer, it is sometimes found to reach deep into the tissue, or to have arisen from a deeper, visceral location. In the latter case, the outcome is often fatal.


This type of cancer can affect any breed of cat at any age, but the incidence of this type of cancer remains relatively rare in cats. Moreover, it is thought to affect cats with lighter skin or hair that spend excessive amounts of time in the sun.


Symptoms and Types


These masses are most commonly present on the cat’s hind limbs, prepuce, and ventral abdomen, but may appear at any place on the body. The tumors may also change in size due to bleeding inside the growth. The following are symptoms related to hermangiosarcoma in cats:


  • Solitary mass or multiple masses on the skin
  • Nodules on skin are raised, firm, and dark
  • Nodules are usually not ulcerative
  • In subcutaneous tissue, masses are firm but soft, and fluctuate underneath
  • Bruising appearance may be present on masses




Although the cause of hemangiosarcoma of the skin is unknown, it is known that light colored and short coated cats are more predisposed to skin cancer than others.  




Your veterinarian will perform a thorough physical exam on your cat, taking into account the background history of symptoms and possible factors that might have led to this condition. You will need to give a thorough history of your cat's health and onset of symptoms, including any details you have about your cat's breed and familial background, the types of activities your cat takes part in, and any physical or behavioral changes that might have taken place recently.


Routine laboratory tests will include a chemical blood profile and complete blood count. The results of these tests are usually normal but may show an abnormally low number of platelets (cells involved in blood clotting). Abdominal and thoracic X-rays will be taken to determine how invasive the hemangiosarcoma is, whether there is metastasis in the lungs or any other internal organs. In some cases, the tumor may even reach to the bone. Computer tomography (CT) scan and magnetic resonance imaging (MRI) can also be used to view the extent of the disease and in planning the surgery.


A skin biopsy remains the method of choice for confirmation of diagnosis. Your veterinarian will take a sample of tissue from the mass to have it microscopically examined by a veterinary oncologist. 




The most successful outcome will require surgical removal in combination with chemical therapy. A wide surgical excision of the tumor, along with some of the normal skin tissue surrounding it is typically the most effective treatment. However, if the tumor involves subcutaneous tissue, complete removal may be difficult to achieve.


After the initial surgery, your veterinary oncologist may recommend continued radiation therapy, especially if a complete resection of tumor could not be achieved. Chemotherapy may also be an option, but whether it is used or not will be decided by your veterinary oncologist.


Living and Management


As with other malignant tumors, cats affected with this tumor have a limited lifespan after diagnosis. Surgery, radiotherapy, and chemotherapy may prolong your cat's lifespan, but not significantly. Cats that have been diagnosed and treated for cancer need to be fed a diet that is specifically formulated for them. Your veterinarian will help you to plan a diet for your cat posttreatment.


Postoperative pain is common, and your veterinarian will recommend pain relieving medications for your cat. Do not use any pain medications without his or hers prior approval, since there are some pain killers that may aggravate the bleeding problems in affected cats. Use pain medications with caution and follow all directions carefully; one of the most preventable accidents with pets is an overdose of medication.


After surgery, you should expect the cat to feel sore. The veterinarian will give you pain medication to minimize your cat's discomfort. You will need to set up a place in the house where your cat can rest comfortably and quietly away from other pets, active children, and busy entryways. Setting the cat litter box and food dishes close by will enable your cat to continue to care for itself normally without unduly exertion. You will also need to protect your cat from the harmful effects of sunlight. If your cat spends time on a window sill or at a glass door, a transparent ultraviolet (UV) blocking window cover can be used to limit the amount of UV rays that reach your cat.


Each cat is different, and some will survive longer than others. The location and extent of the tumor will determine the prognosis, but the average time of survival after surgery is often less than one year. Moreover, complete and permanent remission is rare.

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